Thermal printer with single latch, adjustable media storage and centering assemblies and print assembly

ABSTRACT

A direct thermal printer including a latch assembly, a media storage assembly, a media centering assembly, a print assembly, and a temperature sensing member. The latch assembly includes a single latch lever in mechanical communication with latch tabs disposed in the cover of the printer that are received by openings in the base of the printer to engage and disengage the cover from the base. The media storage assembly includes media guides with removable tabs having more than one available position to provide storage of different size media. The media centering assembly includes pulley assemblies that bias the media guides towards each other to secure media between the media guides. The print assembly includes a platen disposed in the base of the printer having cams on each end that are rotatable and positioned to adjust printing characteristic of a printhead disposed in the cover.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority and the benefit of U.S. applicationSer. No. 14/099,295, filed on Dec. 6, 2013, which claims priority andthe benefit of U.S. Provisional Application Ser. No. 61/734,406, filedDec. 7, 2012, the entirety of which is hereby incorporated by referenceherein for all purposes.

BACKGROUND

Technical Field

The present disclosure relates generally to printers, and in particular,to a direct thermal printer with a single latch assembly, an adjustablemedia storage assembly guide, a media centering assembly, a printassembly, and a temperature sensing member.

Description of Related Art

Direct thermal printers are used to produce a printed image byselectively heating specially coated media as it passes over theprinter's thermal printhead. An image is produced where the media'scoating turns black in the areas where it is heated. Traditional thermalprinters include a thermal printhead, which generates heat andeffectively prints on the media, a platen, or roller (typically rubber),that feeds the media through the printer, a spring or similar mechanismthat urges the thermal printhead toward the media to establish physicalcontact between the printhead and the media to facilitate thermalprinting, and a controller that controls the printer.

SUMMARY

An example embodiment of the present disclosure includes a printer, suchas a direct thermal printer, that comprises a housing including a coverand a base connected together with a hinge, a latch assembly disposed inthe cover, a media storage assembly disposed in the base, a mediacentering assembly disposed in the base, a print assembly disposed inthe housing, and a temperature sensing member disposed in the base.

The latch assembly includes a latch lever disposed at least in part onthe exterior of the cover in mechanical communication with latch tabsalso disposed in the cover such that actuation of the latch lever willsimultaneously actuate the first and second latch tabs. Openings in thebase of the printer are adapted to receive the latch tabs. Once insertedinto the openings, actuation of the latch tabs will move the latch tabsbetween a locked position and an unlocked position allowing the cover tobe selectively engaged and disengaged from the base.

The media storage assembly includes media guides each having tab slotsfor receiving removable and repositionable tabs. The media guides alsoinclude securing tabs for securing the removable and repositionable tabsin the tab slots. The removable and repositionable tabs include a malefeature disposed on the face of each tab. In a first position in the tabslot, the removable and repositionable tab's male feature is in aposition to hold media of a certain size. When the removable andrepositionable tab is repositioned to a second position in the tab slot,the removable and repositionable tab's male feature is in a position tohold media of another inside diameter (ID) core size.

The media centering assembly includes mounting plates disposed on themedia guides and pulley assembly disposed in the base. Each pulleyassembly includes a belt that is attached at one end to one media guideand at the other end to the other media guide. An extension springdisposed in the base is secured to the base at a first end and to one ofthe mounting plates at its other end. The extension spring provides aforce to bias the first media guide towards the second media guide.

The print assembly includes a printhead disposed in the cover andretained by an inner cover frame and positioned by compliant membersthat apply a force against a platen disposed in the base retained by abearing and having a cam disposed at both ends of the platen. Thecompliant members of the printhead provide limited radial movement ofthe printhead along the printhead's axis. The platen's bearing providesradial movement of the platen along the platen's axis. The printassembly further includes a set screw disposed in the base and a leafspring disposed on the platen's bearing and also in contact with the setscrew. Rotation of the set screw rotates platen's cams and this rotationcauses contact of the first and second cams with the printhead whichpositions the printhead forward along the axis of the paper motion.

The printer optionally includes a temperature sensing member disposed inthe base to sense the temperature of certain components.

In another aspect, the present disclosure is directed to a mediacentering assembly. The media centering assembly includes a first mediaguide and a second media guide disposed in slidable opposition to oneanother and configured to support a roll of media therebetween. Themedia centering assembly includes a first pulley assembly having a firstpulley and a first belt. The first belt is in communication with thefirst pulley and is operably coupled to the first media guide at a firstend of the first belt, and the first belt is operably coupled to thesecond media guide at a second end of the first belt. The mediacentering assembly includes a second pulley assembly having a secondpulley and a second belt, wherein the second belt is in communicationwith the second pulley and is operably coupled to the second media guideat a first end of the second belt, and the second belt is operablycoupled to the first media guide at a second end of the second belt. Anextension spring is operably coupled, at a first end of thereof, to ananchor, and the extension spring operably coupled to the first mediaguide at a second end of the extension spring. The extension spring isconfigured to bias the first media guide toward the second media guide.

In some embodiments, the media centering assembly includes a firstmounting plate disposed on the first media guide, and a second mountingplate disposed on the second media guide. In some embodiments, the firstbelt is fixed to the first mounting plate at a first end of the firstbelt, and is fixed to the second mounting plate at a second end of thefirst belt. The second belt is fixed to the second mounting plate at afirst end of the second belt, and is fixed to the first mounting plateat a second end of the second belt.

In some embodiments, the first media guide and the second media guideeach include a male protrusion configured for insertion into a supporttube of a media roll. In some embodiments, the male protrusion isdisposed on a reversible member having a first position wherein the maleprotrusion is configured for insertion into a support tube of a mediaroll having a first diameter, and a second, reversed position, whereinthe male protrusion is configured for insertion into a support tube of amedia roll having a second diameter different from the first diameter.In some embodiments, the first media guide and the second media guideinclude a tab slot defined therein, and the reversible member includes atab configured to selectively engage the tab slot of the correspondingfirst or second media guide.

In another aspect, the present disclosure is directed to a printer thatincludes a housing having a cover and a base connected together with ahinge. A latch assembly is disposed in the cover. The latch assemblyincludes a latch lever disposed at least in part on the exterior of thecover in mechanical communication with a first latch tab and a secondlatch tab, such that actuation of the latch lever simultaneouslyactuates the first and second latch tabs. The base includes first andsecond openings defined therein that are adapted to receive the firstand second latch tabs respectively, wherein the actuation of the firstand second latch tabs once inserted into the first and second openingswill move the latch tabs from a locked position to an unlocked positionallowing the cover to be disengaged from the base. The printer includesa print assembly disposed in the housing having a bearing disposed inthe base, and an elongate cylindrical platen disposed in the base androtatable about its longitudinal axis. The platen is retained by thebearing and the bearing facilitates rotation of the platen along theplaten's longitudinal axis. The print assembly includes a first camdisposed on a first end of the platen, and, a temperature sensordisposed in the base.

In some embodiments, the printer includes a second cam disposed on asecond end of the platen, a set screw disposed in the base, and, a leafspring disposed on the second bearing and in contact with the set screw.Rotation of the set screw rotates the first and second cams and, inturn, rotation of the first and second cams causes contact of the firstand second cams with a printhead. In some embodiments, an anchor slot isdefined in the base that is configured to receive a portion of the leafspring. In some embodiments, the leaf spring is configured fordeflection in a transverse direction away from the platen to enable theleaf spring to move out of the anchor slot.

In some embodiments, the bearing is configured for selective removalfrom the platen by rotating the bearing relative to the platen by apredetermined amount. In some embodiments, the predetermined amount ofrotation is about 43 degrees.

In some embodiments, the printer includes a motor operably coupled tothe platen. In some embodiments, the printer includes a temperaturesensor configured to sense the temperature of the motor. In someembodiments, the temperature sensor provides closed loop temperaturecontrol of the motor.

In yet another aspect, the present disclosure is directed to a printerthat includes a housing having a cover and a base connected togetherwith a hinge. The printer includes a latch assembly disposed in thecover. The latch assembly includes a latch lever disposed at least inpart on the exterior of the cover in mechanical communication with afirst latch tab and a second latch tab. Actuation of the latch leversimultaneously actuates the first and second latch tabs. The baseincludes first and second openings defined therein to receive the firstand second latch tabs respectively. Actuation of the first and secondlatch tabs, once inserted into the first and second openings, move thelatch tabs from a locked position to an unlocked position thus allowingthe cover to be disengaged from the base. The printer includes a mediacentering assembly disposed in the base. The media centering assemblyincludes a first media guide and a second media guide disposed inslidable opposition to one another and configured to support a roll ofmedia therebetween. The media centering assembly includes a first pulleyassembly having a first pulley and a first belt. The first belt is incommunication with the first pulley and is operably coupled to the firstmedia guide at a first end of the first belt, and is operably coupled tothe second media guide at a second end of the first belt. The mediacentering assembly includes a second pulley assembly that includes asecond pulley and a second belt. The second belt is in communicationwith the second pulley and is operably coupled to the second media guideat a first end of the second belt, and operably coupled to the firstmedia guide at a second end of the second belt. The media centeringassembly includes an extension spring operably coupled to an anchor at afirst end of the extension spring, and is operably coupled to the firstmedia guide at a second end of the extension spring and configured tobias the first media guide toward the second media guide.

In some embodiments, the printer includes a first mounting platedisposed on the first media guide, and a second mounting plate disposedon the second media guide. In some embodiments, the first belt is fixedto the first mounting plate at a first end of the first belt, and isfixed to the second mounting plate at a second end of the first belt.The second belt is fixed to the second mounting plate at a first end ofthe second belt, and is fixed to the first mounting plate at a secondend of the second belt. In some embodiments, the first media guide andthe second media guide each include a male protrusion configured forinsertion into a support tube of a media roll. In some embodiments, themale protrusion is disposed on a reversible member having a firstposition wherein the male protrusion is configured for insertion into asupport tube of a media roll having a first diameter, and a second,reversed position wherein the male protrusion is configured forinsertion into a support tube of a media roll having a second diameterdifferent from the first diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present subject matter may take form in various components andarrangements of components, and in various steps and arrangements ofsteps. The appended drawings are only for purposes of illustratingparticular embodiments and are not to be construed as limiting thesubject matter.

FIG. 1 is a front perspective view of an assembled thermal printerconstructed in accordance with an example embodiment of the presentdisclosure;

FIG. 2 is a front perspective view of an assembled thermal printer shownwith its cover open and constructed in accordance with an exampleembodiment of the present disclosure;

FIG. 3A is a perspective view of the media storage assembly inaccordance with an example embodiment of the present disclosure;

FIG. 3B is a perspective view of exemplary media that may be used in anexample embodiment of the present disclosure;

FIG. 4 is a top perspective view of the media centering assembly inaccordance with an example embodiment of the present disclosure;

FIG. 5 is a perspective view of the portion of the print assemblyincluding a portion of the platen and the cam located at one end of theplaten constructed in accordance with an example embodiment of thepresent disclosure;

FIG. 6 is a side perspective view of the portion of the print assemblyincluding a portion of the platen and the cam located at one end of theplaten, the drive train, and a temperature sensing member constructed inaccordance with an example embodiment of the present disclosure; and

FIG. 7 is a circuit drawing of the temperature sensing memberconstructed in accordance with an example embodiment of the presentdisclosure.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are describedhereinbelow with reference to the accompanying drawings; however, it isto be understood that the disclosed embodiments are merely examples ofthe disclosure, which may be embodied in various forms. Well-knownand/or repetitive functions and constructions are not described indetail to avoid obscuring the present disclosure in unnecessary orredundant detail. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as abasis for the claims and as a representative basis for teaching oneskilled in the art to variously employ the present disclosure invirtually any appropriately detailed structure. In addition, as usedherein in the description and in the claims, terms referencingorientation, e.g., “top”, “bottom”, “upper”, “lower”, “left”, “right”,and the like, are used with reference to the figures and features shownand described herein. It is to be understood that embodiments inaccordance with the present disclosure may be practiced in anyorientation without limitation. In this description, as well as in thedrawings, like-referenced numbers represent elements which may performthe same, similar, or equivalent functions.

Turning first to FIGS. 1 and 2, according to aspects of the presentdisclosure, direct thermal printer 100 includes base 110 and cover 120.Cover 120 is configured for selective engagement with a top portion ofbase 110 and includes top frame 180, latch lever 140, and latch tabs220. In the present embodiment, top frame 180 includes an enlargedsection of a top surface 121 of cover 120, and is generally configuredto allow cover 120 to couple with base 110 without contacting orinterfering with the supply of print media 150 disposed within printer100. Additionally, cover 120 may be hingedly attached to a rear portionof the base at hinge 130. Various structures known in the art tohingedly attach cover 120 to base 110 are also contemplated, for exampleand without limitation, a conventional hinge-pin arrangement, a livinghinge, and so forth. During use, cover 120 may be pivoted or rotatedabout hinge 130 to enable a user to selectively access the components inbase 110, to load and unload media, and the like. A view of printer 100with cover 120 open and media inserted is shown in FIG. 2.

Latch lever 140 can be mechanically connected to latch tabs 220 whichcan be disposed on opposing sides of cover 120. Latch tabs 220 can benormally biased for engaging slots 230 located in base 110. Actuation oflatch lever 140 can simultaneously actuate latch tabs 220, whichovercomes the bias such that latch tabs 220 do not engage slots 230 inbase 110 and cover 120 can be pivoted about hinge 130 or separated frombase 110. Conversely, the normal bias of latch tabs 220 urges latch tabs220 to engage a portion of slots 230 thereby securing cover 120 to base110.

Front plate 160 of base 110 provides an exit surface over which media150 passes as it exits printer 100. Front plate 160 may be pulled awayfrom base 110 to provide space for the attachment of optionalaccessories, such as a label peeler and/or a cutter, to base 110.

Printer 100 can be supplied with power from an electrical source (notshown). The electrical source of energy can be AC or DC depending on thedesired configuration of printer 100. Switches or buttons 170 can bepositioned on the top face of cover 120 and can be in electricalcommunication with a control circuit (not shown) that is disposed withinprinter 100. The control circuit can be a printed circuit board or anycontrol circuit known in the art sized to fit in printer 100. Buttons170 can control operation of printer 100 such as pause, resume, andfeed.

Media storage assembly 300, which can be seen only partially in FIG. 2,is shown in further detail in FIGS. 3A and 4. Media storage assembly 300includes spaced apart media guides 310 each having tab slots 320 forreceiving removable tabs 330 which may be selectively positioned withintab slots 320. Media guides 310 can also include securing tabs 340 forsecuring removable tabs 330 in tab slots 320. Removable tabs 330 caninclude disc-shaped male features 350 disposed on the face of removabletabs 330. Male features 350 are adapted for engaging a portion of theinside diameter of media supply roll 152. Various types of media 150 mayhave an inside diameter of varying sizes. For example, as illustrated inFIG. 3B, media supply roll 152 a has an inside diameter 360 a ofdiameter d_(a), while media supply roll 152 b has an inside diameter 360b of diameter d_(b) that is greater than diameter d_(a).

Media supply roll 152, media supply roll 152 a, and/or media supply roll152 b may include a support tube 151, support tube 151 a, and/or supporttube 151 b, respectively, that engages male feature 350 such that mediasupply roll 152 is rotatable on male features 350, thereby allowingmedia 150 to be fed from media supply roll 152 toward printhead 510.Media guides 310 can be repositioned within tab slots 320 to allow formedia supply rolls 152 of different inside diameters to fit in printer100. In a first position in tab slot 340, which is indicated by 330 a,removable tab's 330 male feature 350 is in a position to hold mediarolls of a certain size, for example, a media supply roll having a widthof 1.5 inches. When removable tab 330 is removed, rotated 180 degrees,and reinserted in a second position, which is indicated by 330 b, in thetab slot, removable tab's 330 male feature 350 is placed in a positionsuitable to hold media of another size, for example, 1.0 inches wide.

Turning now to FIG. 4, media centering assembly 400 is shown in furtherdetail. Media centering assembly 400 may include mounting rails (notshown) disposed in base 110, first and second mounting plates 410disposed on first and second media guides 310, and pulley assemblies 415a and 415 b disposed in base 110. Pulley assembly 415 a includes pulley420 a and belt 430 a. As shown in FIG. 4, belt 430 a can be attached toa first mounting plate 410 with fastener 440 a and to a second mountingplate 410 with fastener 440 b. Pulley assembly 415 b includes pulley 420b, belt 430 b, and extension spring 450. As shown in FIG. 4, belt 430 bis joined to one of mounting plates 410 with fastener 440 c and to theother media of mounting plates 410 with another fastener (not shown).Although fasteners are illustrated here, any attaching mechanisms knownin the art are contemplated by the present disclosure, including withoutlimitation, threaded fasteners, rivets, clips, adhesive, integralforming, overmolding, intermolding, and so forth. Mounting plates 410are slidably mounted to the mounting rails (not shown) such thatmovement of mounting plates 410 and guides 310 is directed in atransverse linear path. Extension spring 450 is disposed between one ofmounting plates 410 and an anchor 451 situated on a portion of base 110that is opposite mounting plate 410, such as the platen bracket (notshown), an interior wall of base 110, or any other suitable position.Extension spring 450 is biased for pulling media guides 310 a, 310 btowards each other.

During use, in order to insert a media roll 152 on male features 350, auser pushes apart media guides 310 thus extending extension spring 450to overcome the bias thereof. After media roll 152 is positioned onmedia guides 310, e.g., male features 350 are inserted into support tube151 of media roll 15, the user releases media guides 310, which, inturn, causes extension spring 450 to contract, thus allowing the mediaguides 310 to pull towards each other and thereby hold media roll 152 inplace. Advantageously, the interaction of belt 430 a and pulley 420 awith left media guide 310 a and right media guide 310 b, the interactionof belt 430 b and pulley 420 b with left media guide 310 a and rightmedia guide 310 b, together with the inward bias of extension spring450, enables media guides 310 to move in a reciprocal manner about thecenterline A-A (FIG. 2) of printer 100, which, in turn, enables mediaguides 310 to retain media roll 152 in a centered position relative toprinthead 510. In this manner, centering of the print media roll 152 maybe achieved without the bulk and friction typically encountered withconventional rack and pinion arrangements.

Print assembly 500, which is shown partially in FIG. 2, is disposedwithin base 110 and/or within cover 120. A portion of print assembly 500that may be disposed in cover 120 includes inner cover 562, compliantmembers (such as compression springs—not shown) and printhead 510. Innercover 562 and compliant members can retain printhead 510 providinglimited radial movement of printhead 510 along printhead 510's axis.

The portion of print assembly 500 is shown in further detail in FIG. 5.Bearing 550 retains platen 520 and facilitates axial rotation of platen520 along a longitudinal axis thereof. A cam 530 is disposed at each endof platen 520. An adjustment set screw 560 is disposed in base 110. Leafspring 540 is disposed at a first end 541 on the bearing 550 and at asecond end 542 in slot 545. When positioned in slot 545, leaf spring 540contacts a set screw 560. Rotation of set screw 560 engages leaf spring540, which, in turn, rotates cam 530. As cam 530 rotates, printhead 510is translated in a longitudinal direction (e.g., along axis A-A). Inthis manner, the position of printhead 510 may be adjusted to achieveoptimal printing. Set screw 560 includes a tool engaging feature 561,such as a slot, Phillips head, Pozidrive head, hex head, Torx head, andthe like to facilitate the adjustment thereof with a screwdriver orother suitable tool. In some embodiments, set screw 560 may be knurledto enable adjustment using only the fingers. Leaf spring 540 is biasedinward, e.g., toward platen 520, to retain platen 520 in associationwith bearing 550. During use, leaf spring 540 may be deflected in atransverse direction away from platen 540 (e.g., orthogonal to axis A-A)to allow leaf spring 540 to move out of its anchor position in base 110.Once bearing 550 is rotated a predetermined amount, for example, about43 degrees, bearing 550 may be removed from the platen bracket (notshown) to facilitate the removal and replacement of platen 520, bearing550, leaf spring 540 and/or set screw 560.

Printer 100 also includes motor 605 as shown in FIG. 6. Motor 605, whichmay be a stepper motor, a DC motor, an AC motor, or any suitable motornow or in the future known, is operatively coupled to platen roller 520via drive train 620 such that a full step of motor 605 corresponds to apredetermined length of media 150 movement. Temperature sensor 610,which may include a thermistor, and drive train 620, are shown in FIG.6. Temperature sensor 610 is disposed in base 110 and is configured tosense and/or monitor the temperature of motor 605, providing closed looptemperature control of motor 605 which, in turn, allows printer 100 torun at higher duty cycles and protect the printer 100 and/or motor 605from overheating.

FIG. 7 shows a stepper motor interface 700 which illustrates theelectrical connections of the temperature sensor 610 to ananalog-to-digital converter (ADC) input 612 of the printer controller(not shown), which is used to determine motor temperature. In theillustrated embodiment, motor 605 employs a four-wire arrangement inwhich the relative timing of the phase A 614 and phase B 616 motor drivesignals, as provided by the controller, determines the rotational outputof motor 605 and thus, the advancement of media 150.

The described embodiments of the present disclosure are intended to beillustrative rather than restrictive, and are not intended to representevery embodiment of the present disclosure. Further variations of theabove-disclosed embodiments and other features and functions, oralternatives thereof, may be made or desirably combined into many otherdifferent systems or applications without departing from the spirit orscope of the disclosure as set forth in the following claims bothliterally and in equivalents recognized in law.

What is claimed is:
 1. A media centering assembly, comprising: a firstmedia guide and a second media guide configured to support a roll ofmedia therebetween; and a single extension spring operably coupled to ananchor and to the first media guide, the extension spring is configuredto bias the first media guide toward the second media guide.
 2. Themedia centering assembly in accordance with claim 1, further comprisinga first pulley assembly that includes: a first pulley; and a first beltin communication with the first pulley and operably coupled between thefirst media guide and the second media guide.
 3. The media centeringassembly in accordance with claim 2, further comprising a second pulleyassembly that includes: a second pulley; and a second belt communicationwith the second pulley and operably coupled between the first mediaguide and the second media guide.
 4. The media centering assembly inaccordance with claim 3, further comprising: a first mounting platedisposed on the first media guide; and a second mounting plate disposedon the second media guide.
 5. The media centering assembly in accordancewith claim 4, wherein the first belt and the second belt are fixedbetween the first mounting plate and the second mounting plate.
 6. Themedia center assembly in accordance with claim 1, wherein the firstmedia guide and the second media are disposed in slidable opposition toone another.
 7. A printer comprising: a housing including a cover and abase connected together with a hinge; a latch assembly disposed in thecover, the latch assembly including a latch lever disposed at least inpart on the exterior of the cover in communication with a first latchtab and a second latch tab such that actuation of the latch leversimultaneously actuates the first and second latch tabs; first andsecond openings defined in the base adapted to receive the first andsecond latch tabs respectively, wherein after insertion into the firstand second openings, actuation of the first and second latch tabs movesthe latch tabs from a locked position to an unlocked position allowingselective disengagement of the cover from the base; and a print assemblydisposed in the housing.
 8. The printer assembly in accordance withclaim 7, wherein the print assembly includes: a first bearing disposedin the base, a platen rotatable about longitudinal axis thereof anddisposed in the base; a first cam disposed on a first end of the platen;and a temperature sensor disposed in the base.
 9. The printer inaccordance with claim 8, further comprising: a second cam disposed on asecond end of the platen; a set screw disposed in the base; and a leafspring disposed on a second bearing and in contact with the set screw,wherein rotation of the set screw causes the first and second cams tocome in contact with a printhead.
 10. The printer in accordance withclaim 9, wherein the base includes an anchor slot defined thereinconfigured to receive a portion of the leaf spring.
 11. The printer inaccordance with claim 8, further comprising a motor operably coupled tothe platen.
 12. The printer in accordance with claim 11, wherein thetemperature sensor is configured to sense the temperature of the motor.13. The printer in accordance with claim 12, wherein the temperaturesensor provides closed loop temperature control of the motor.
 14. Aprinter according to claim 7 further comprising: a media centeringassembly disposed in the base, including: a first media guide and asecond media guide configured to support a roll of media therebetween;and an extension spring operably coupled to an anchor and to the firstmedia guide, the extension spring is configured to bias the first mediaguide toward the second media guide.